System and method for obtaining optical signal information

ABSTRACT

A system is provided for identifying signal propagation information. The system includes at least one component configured to receive an optical input signal and to emit an optical output signal. The emitted optical output signal is representative of the optical input signal, and is associated with characteristic information indicative of the component. A processor is also included, the processor being configured to sense the optical output signal and correlate the characteristic information with said component.

BACKGROUND INFORMATION

Optical networks are increasingly relied upon for communications anddata transfer activities. However, while many data transfer activitiesinvolve communications across large geographical distances, the spatialexpanse of “proprietary networks,” or those networks controlled byindividual network providers, is often somewhat more limited. As aresult, some network providers have sought to implement a system inwhich each network provider shares access to its own proprietarynetwork, or “domain,” with other network providers. In that case,optical signals would be passed from one domain to another, therebyexpanding the spatial communications capabilities of all users. Byemploying such a system, network providers hope to enable national andinternational communications services in line with customer demands.

One of the significant obstacles to the above system of network sharingis ensuring network interoperability, or the ability of one domain toeffectively receive, process, and/or propagate optical signals fromanother domain. Specifically, in many cases, network providers arerelated to the communications service providers, and the various domainsare configured to be consistent with specific communications methods andprotocols. Components included in the network forming each domain, whilewell-suited for handling intra-domain optical signals, are oftenill-suited to interacting with inter-domain optical signals, due to aninability to recognize degradation of the signals. Until recently,solutions to this issue focused on mainly software-implementedstrategies to allow optical signals to be recognized by differentdomains. However, software solutions have failed to completely solve theproblem, due to the requirement to reveal proprietary networkinformation in order to create the software. As such, there is a needfor an optical communications system in which domain interoperability isenhanced.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic perspective view of a portion of an opticalnetwork, the network being configured in accordance with an embodimentof the present invention;

FIGS. 2 a-2 c are a sequential schematic representation of a signal spropagating along a wave guide connecting several components thatintroduce characteristic information associated with the signal; and

FIG. 3 is a schematic representation of a signal propagating along awave guide, the signal being shown at three sequential points in timeincluding before encountering several optical network component andafter encountering one and both of the components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The preferred embodiments according to the present invention now will bedescribed more fully hereinafter with reference to the accompanyingdrawings, in which some, but not all embodiments of the inventions areshown. Indeed, these inventions may be embodied in many different formsand should not be construed as limited to the embodiments set forthherein; rather, these embodiments are provided so that this disclosurewill satisfy applicable legal requirements. Like numbers refer to likeelements throughout.

Referring to FIG. 1, therein is shown a portion of an optical network100, the illustrated portion being configured in accordance with anembodiment of the present invention. The network portion 100 includesmultiple optical paths, such as free-space areas 102 for propagation ofoptical or electromagnetic waves and discrete waveguides 104, such asoptical fibers. Both the free-space links 102 and the wave guides 104are capable of supporting the propagation of signals. The networkportion 100 may be part of a larger network, or may be independentlyutilized. If the network portion is part of a larger network, thatlarger network may be exclusively optical, may include electrical andoptical aspects, may utilize only electrical components that couple tothe illustrated network portion via an electrical-to-optical converter,or may include aspects that support the propagation of other types ofsignals, such as, for example, pressure or stress waves.

Multiple components 106 may be included in the network portion 100,interconnected by the optical paths 102, 104. When the components 106are connected in this way, signals may propagate between the componentsand along and through the network portion 100. Each of the components106 can be configured to receive an input signal propagating on anoptical path and to emit an output signal. At least some of these outputsignals can be representative of the input signals, such thatinformation contained in the input signal is generally retained andfurther propagated in the related output signal; an example of such arepresentative output signal is described in more detail below. Someoutput signals may also be associated with characteristic informationthat includes characteristic features indicative of the subset ofcomponents 106 that has been encountered by the signal (i.e., the signalthat generated the output signal) during propagation through the networkportion 100. Examples of characteristic information and characteristicfeatures are also included below. In some embodiments, characteristicinformation might also include information regarding the content orformat of the signal. For example, some of the characteristicinformation might indicate the wavelength of an associated opticalsignal.

Network portion 100 also includes a processor 108 configured forobtaining characteristic information and correlating such information,respectively, with one or more of the components 106. As used herein,processor 108 is to be broadly construed to include any type ofcomputing device or other hardware or software component capable ofperforming the functions described below in conjunction with theprocessor. In terms of obtaining the characteristic information, theprocessor 108 may be coupled to an optical path, typically via anoptical-to-electrical converter, and incorporate the capability to sensesignals and associated characteristic information, may be incommunication or integrated with a component 106, or may be coupled toanother device that is capable of sensing a signal and/or associatedcharacteristic information and relaying such information to theprocessor 108. A memory 110 can also be included in the network portion100, memory 110 being in communication with processor 108. For example,memory 110 could store and communicate to the processor 108 a signal andassociated characteristic information. The memory 110 could also storeinstructions or software that cause the processor to obtain the signaland associated characteristic information, either from the memory orotherwise, as well as instructions causing the processor to correlatethe characteristic information with at least one component.

By correlating the characteristic information with at least one of therespective components, processor 108 might determine one or all of thecomponents 106 that a signal has encountered while propagating onnetwork portion 100. Processor 108 might also determine the pathfollowed by the signal in traversing the network portion 100, as well asthe actual or likely signal intensity and/or degradation due, forexample, to dissipation in the components encountered and/or the waveguides. In some embodiments, multiple processors may be included in thenetwork portion, perhaps by coupling a respective processor to each, orat least a plurality, of the components. The inclusion of multipleprocessors might allow for analyzing signals throughout significantportions, if not all, of the network portion. In some cases, theprocessor may be configured to correlate the characteristic informationassociated with a signal with substantially all of the respectivecomponents that the signal has encountered. This configuration mightfacilitate the tracing of a signal through a network being traversed bythe signal.

As mentioned, processor 108 may be employed to determine the intensityof a signal based on the characteristic information. Along these lines,the processor 108 may be configured to determine the intensity of asignal reaching a specific component. The processor can then instructthe component associated with the processor, such as component 106′ inFIG. 1, to dispose of the signal in an appropriate manner based on theintensity of the signal. For instance, if the signal intensity is low,the processor can instruct the component to emit a related outputsignal, for example, by emitting an amplified version of the inputsignal, for further propagation through the network portion. Conversely,if signal intensity is high, the processor may instruct the component tosimply transmit the signal. In some cases, the processor may instructthe component to terminate the signal. This can involve communicatingthe content of the signal to a separate device, such as a monitor fordisplaying the content or a cellular phone for receiving the content.

Referring to FIGS. 2 a-2 c, therein are shown sequential schematicrepresentations of a signal s 220 propagating along a wave guide 204connecting several components 206 a-b. First, signal (s) 220 is shownpropagating along a waveguide 204 toward a component 206 a. Once signal220 encounters component 206 a, characteristic information 222 isintroduced such that the characteristic information 222 is associatedand travels with signal 220. The characteristic information 222 includescharacteristic feature (CF_(a)) 224 indicative of the fact that signal220 has encountered component 206 a. As signal 220 and characteristicinformation 222 continue to propagate along waveguide 204, component 206b is encountered. As a result, characteristic feature (CF_(b)) 226 isintroduced such that it is associated and travels with signal 220.Characteristic feature 226 is indicative of the fact that the signal 220has encountered component 206 b. As shown in FIG. 2 c, the output signalfrom component 206 b not only includes signal (s), but also both CF_(a)and CF_(b) such that any subsequent analysis of the output signal candetermine that the path of the signal (s) included components 206 a and206 b as a result of the inclusion of CF_(a) and CF_(b), respectively.

Various types of components might be included in the network portiondiscussed above. For example, network components can include tunableoptical devices, such as reconfigurable optical add/drop multiplexers(ROADM). Components can also include transponders, optical amplifiers,waveguides, lenses, beam splitters, and mirrors. Specifically, ditheringfunctions, such as those sometimes employed in conventional networks andfacilitated by transponders and/or mirrors, can serve to incorporatecharacteristic features into a propagating signal. By using a specificdithering tone for each transponder or for related groups oftransponders, a signal can incorporate a set of characteristic featuresindicative of the path followed by the signal through the networkportion.

Components can be configured to introduce characteristic feature suchthat each component introduces a unique characteristic feature. In thisway, a processor might track the exact components encountered by apropagating signal. Alternatively, components may introducecharacteristic features that are indicative of a type of component, aspatial location, or the owner/operator of the equipment, but which arenot necessarily unique to one component. In this case, a processor maybe able to generally determine the origin, path, and/or distancetraveled by a signal in a network, although it may still be possible todetermine an exact signal route based on correlations between intensityand characteristic information. Moreover, by appending thecharacteristic features in a predefined order, the processor can alsodetermine the corresponding order in which a propagating signalencountered the components. This may also be possible when thecharacteristic features are not specified in a predefined order, throughde-convolution techniques.

As an example of the manner in which characteristic information might beassociated with a signal, referring to FIG. 3, therein is shown aschematic representation of a signal propagating along a wave guide 304.The signal is shown at three sequential points in time, from time t₀where the signal is approaching component 306 a to a time t₁ where thesignal is beyond component 306 a and approaching component 306 b, andthen to a time t₂ where the signal has passed component 306 b. At t₀,the signal can be represented by a sinusoidal wave with a wavelength ofλ_(s) and an amplitude of A_(s). This, for instance, is the responseover time sensed by a receiver of the signal.

At a time between t₀ and t₁, the signal encounters component 306 a. Oncethe signal has encountered component 306 a at t₁, the amplitude of theoriginal sinusoid is increased to A_(s)′ while the wavelength hasremained at λ_(s). As such, the component 306 a has amplified theoriginal signal, but has emitted a signal that is representative of theoriginal (in this case, has the same wavelength λ_(s)). Component 306 ahas also acted to superimpose or modulate another wave onto the originalsinusoid. The superimposed wave has a wavelength λ_(a) and is aggregatedwith the original wave to yield a composite wave characterized by thewaveform shown at t₁. This superimposed wave may act as thecharacteristic feature of component 306 a, being indicative of theinteraction between the signal and the component.

As the signal continues to propagate along wave guide 304, the signalencounters at a time between t₁ and t₂ the component 306 b. Followingthis encounter at t₂, another wave has been superimposed onto thesignal. The newly superimposed wave has a wavelength of λ_(b). Thesuperposition yields a composite wave that may be represented by thewaveform shown at t₂. Still contained by the composite wave is acomponent with amplitude of A_(s)′ and a wavelength of λ_(s). Thiscomposite wave, therefore, continues to be representative of theoriginal signal, although amplified. Further, the wave now includes acomponent with a wavelength λ_(b), and this may act as thecharacteristic feature of the component 306 b.

As mentioned, the waveform representing the signal at time t₂ includesseveral different harmonic frequencies which act as the characteristicfeatures. In one embodiment, the characteristic features can beextracted by performing a frequency transformation on the wave toseparate the components of different wavelength, as is well known. Thistransformation can be carried out, for example, by a processor, perhapsin a conventional computer. Alternatively, components can be used forphysically separating the signal from the characteristic information,perhaps by employing a band pass filter that allows transmission of thesignal but not the other components of the propagating wave. Ininstances in which it is desirable to be able to individually identifythe components through which the signal passed, the wavelengths λ_(a)and λ_(b) that are superimposed upon the signal may be unique to and,therefore, characteristic of components 306 a and 306 b.

The characteristic information can be introduced such that theinformation leads, trails, or is commingled with the signal, or could besome combination thereof. In some embodiments, at least one of thesignals may be included in an electromagnetic wave. In these cases,characteristic features may be introduced in the form of electromagneticradiation of one or more wavelengths. In one embodiment, one componentmay be a transponder that introduces electromagnetic radiation of one ormore wavelengths via a dithering tone of the transponder. Dithering maybe amplitude dithering, frequency dithering, or a combination of thetwo. Signals and characteristic information can be amplitude modulated,frequency modulated, or a combination.

Many modifications of the preferred embodiments set forth herein andother embodiments will be evident based on the teachings presented inthe foregoing descriptions and the associated drawings. Therefore, it isto be understood that the inventions are not to be limited to thespecific embodiments disclosed and that modifications and otherembodiments are intended to be included within the scope of the appendedclaims. Although specific terms are employed herein, they are used in ageneric and descriptive sense only and not for purposes of limitation.

1. A method comprising: receiving a propagating optical signal that haspropagated through a plurality of optical network components of anoptical network; extracting characteristic information from thepropagating optical signal; identifying the extracted characteristicinformation associated with the propagating optical signal, thecharacteristic information being introduced by at least two of theoptical network components encountered by the propagating opticalsignal, where the characteristic information includes a first wavesuperimposed on the propagating optical signal by one of the at leasttwo optical network components, and where the characteristic informationincludes a different second wave superimposed on the propagating opticalsignal by another of the at least two optical network components; andcorrelating the characteristic information with the at least two onerespective optical network components encountered by the propagatingoptical signal, where the correlating includes: determining that anetwork path through which the propagating optical signal has propagatedincludes the at least two optical network components.
 2. (canceled) 3.The method according to claim 1, where the signal and characteristicinformation are incorporated into a wave, where the extracting includesperforming a frequency transformation on the wave to identify the signaland the characteristic information.
 4. The method according to claim 1,where the correlating includes correlating the characteristicinformation with a subset of the respective optical network componentsto determine an intensity of the propagating signal.
 5. The methodaccording to claim 4, where the characteristic information includes oneor more characteristic features, each characteristic feature beingintroduced by and unique to a respective optical network component ofthe optical network.
 6. A system comprising: a plurality of opticalcomponents, where at least two of the plurality of optical componentsare to: receive an optical input signal, introduce characteristicinformation indicative of the optical component that received theoptical input signal, where when introducing the characteristicinformation, the at least two optical components are each to:superimpose a wave onto the received optical input signal, where a firstwave superimposed by one of the at least two optical components isdifferent from a second wave superimposed by another of the at least twooptical components, and emit an optical output signal representative ofthe optical input signal and associated with the characteristicinformation indicative of the optical component; and a processor to:sense a propagating optical output signal encountered by the at leasttwo optical components and characteristic information associated withthe propagating optical signal encountered by the at least two opticalcomponents, correlate the characteristic information with the at leasttwo optical components, and based on the correlated characteristicinformation, determine a network path through which the propagatingoptical signal has propagated.
 7. The system according to claim 6, wherethe optical input and output signals are included in an electromagneticwave.
 8. The system according to claim 7, where the characteristicfeature is electromagnetic radiation of one or more wavelengths.
 9. Thesystem according to claim 8, where at least one of said opticalcomponents includes a transponder and the electromagnetic radiation ofone or more wavelengths is introduced as a dithering tone of thetransponder.
 10. The system according to claim 7, where the processor isfurther to perform a frequency transformation on the electromagneticwave to identify the signal and the characteristic information.
 11. Thesystem according to claim 6, where the processor is further todetermine, based on the correlation of the characteristic informationwith the optical component, an intensity of the propagating opticalsignal.
 12. The system according to claim 11, where the processor isfurther to instruct one of the optical components to terminate anoptical signal received by the optical component or to emit a relatedoptical output signal.
 13. (canceled)
 14. The system according to claim6, where at least one of the optical components includes at least one ofa transponder, an optical amplifier, a mirror, or a tunable opticalcomponent.
 15. The system according to claim 14, where the tunableoptical component includes a reconfigurable optical add/drop multiplexer(ROADM).
 16. The system according to claim 6, where the processor isfurther to correlate the characteristic information with a wavelength ofat least one of the input signal or the output signal associated with aparticular optical component.
 17. An apparatus comprising: a memory tostore executable instructions; and a processor to execute the executableinstructions, where the executable instructions cause the processor to:obtain an optical signal, identify characteristic information associatedwith the obtained optical signal, the characteristic information beingintroduced by at least one optical network component encountered by theoptical signal, correlate the characteristic information with at leastone respective optical network component, and based on the correlatedcharacteristic information, determine a network path through which theoptical signal has propagated.
 18. (canceled)
 19. The apparatusaccording to claim 17, where the signal and characteristic informationare incorporated into a wave, where the processor is further to extractthe characteristic information by performing a frequency transformationon the wave to identify the signal and the characteristic information.20. The apparatus according to claim 17, where the processor is furtherto correlate the characteristic information with a plurality of opticalnetwork components encountered by the signal.
 21. The apparatusaccording to claim 20, where the characteristic information includes oneor more characteristic features, each characteristic feature beingintroduced by and unique to a respective optical network component of anoptical network.
 22. The apparatus according to claim 20, where theprocessor is further to determine an intensity of the propagating signalbased on the correlating of the characteristic information with theplurality of the respective optical network components encountered bythe optical signal.
 23. (canceled)
 24. (canceled)
 25. The apparatusaccording to claim 17, where the processor is further to generate aninstruction regarding disposition of the signal based on the correlatingof the characteristic information with at least one respective opticalnetwork component.
 26. The method according to claim 1, wheredetermining the network path includes: determining, in order, whichoptical network components of the optical network the propagatingoptical signal has encountered.
 27. The system according to claim 12,where the related optical output signal includes an amplification of theoptical signal received by the optical component.
 28. The methodaccording to claim 17, where the processor is further to identify, inorder, a plurality of optical network components that the optical signalhas encountered.
 29. The method of claim 1, where the first wave has afirst wavelength, and where the second wave has a different secondwavelength.